Reducing Uncertainty in Overpressure Prediction in the Norwegian Barents Sea

Abstract

Pore pressure prediction in the Barents Sea is challenging for a variety of reasons including a complicated and variable burial history (leading to varying magnitudes and timings of burial, hiatus and uplift from well to well), variation in mudrock lithology and depositional environments. These factors can all create uncertainty when predicting pore pressure. Here are introduced two independent methodologies for present day shale pressure prediction across the Barents Sea, focussing in particular in the Southwestern Barents Sea where high overpressure is often recorded. Independent velocity log based and geological modelling based shale pressure prediction methods are used. Comparison of the two models generally shows good consistency in results, helping to validate the predictions and models and reduce uncertainty. This reinforces the need to integrate multiple techniques in order to reduce uncertainty in what is a challenging area for pore pressure prediction. The results also show that understanding the complex and variable burial history in each well is vital for pore pressure prediction, as this history defines the present day pressures. The models developed have clear implications for design of wells in the Barents Sea, and are also important for understanding reservoir overpressure variation (and potential reservoir fluid flow).